From 95193b0bfd4b4e2c2e0c6ef216b4331e2f037cf4 Mon Sep 17 00:00:00 2001
From: alex <alex@slab.org>
Date: Thu, 19 Jun 2025 08:18:20 +0100
Subject: [PATCH 1/4] a test for #1396

---
 packages/core/test/pattern.test.mjs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/packages/core/test/pattern.test.mjs b/packages/core/test/pattern.test.mjs
index 45a1e2a98..b93d80f25 100644
--- a/packages/core/test/pattern.test.mjs
+++ b/packages/core/test/pattern.test.mjs
@@ -52,6 +52,7 @@ import {
   stackCentre,
   stepcat,
   sometimes,
+  expand
 } from '../index.mjs';
 
 import { steady } from '../signal.mjs';
@@ -1179,6 +1180,9 @@ describe('Pattern', () => {
     it('calculates undefined steps as the average', () => {
       expect(sameFirst(stepcat(pure(1), pure(2), pure(3).setSteps(undefined)), fastcat(1, 2, 3)));
     });
+    it('works with auto-reified values', () => {
+      expect(sameFirst(stepcat(expand(3, 'bd'), 'rim'), stepcat(expand(3, 'bd'), pure('rim'))))
+    });
   });
   describe('shrink', () => {
     it('can shrink', () => {

From 440f1cb081c0947ba3ba8b00b33f4dcc74bafe98 Mon Sep 17 00:00:00 2001
From: alex <alex@slab.org>
Date: Thu, 19 Jun 2025 08:27:23 +0100
Subject: [PATCH 2/4] reify arguments of stepcat

---
 packages/core/pattern.mjs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/core/pattern.mjs b/packages/core/pattern.mjs
index 76b02c21e..59833aea7 100644
--- a/packages/core/pattern.mjs
+++ b/packages/core/pattern.mjs
@@ -2720,6 +2720,7 @@ export function stepcat(...timepats) {
     return nothing;
   }
   const findsteps = (x) => (Array.isArray(x) ? x : [x._steps, x]);
+  timepats = timepats.map(reify);
   timepats = timepats.map(findsteps);
   if (timepats.find((x) => x[0] === undefined)) {
     const times = timepats.map((a) => a[0]).filter((x) => x !== undefined);

From a1d181d6097057542ca7dd943a2a8105330f52d5 Mon Sep 17 00:00:00 2001
From: alex <alex@slab.org>
Date: Thu, 19 Jun 2025 08:27:41 +0100
Subject: [PATCH 3/4] format

---
 packages/core/test/pattern.test.mjs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/core/test/pattern.test.mjs b/packages/core/test/pattern.test.mjs
index b93d80f25..07bdcdda7 100644
--- a/packages/core/test/pattern.test.mjs
+++ b/packages/core/test/pattern.test.mjs
@@ -52,7 +52,7 @@ import {
   stackCentre,
   stepcat,
   sometimes,
-  expand
+  expand,
 } from '../index.mjs';
 
 import { steady } from '../signal.mjs';
@@ -1181,7 +1181,7 @@ describe('Pattern', () => {
       expect(sameFirst(stepcat(pure(1), pure(2), pure(3).setSteps(undefined)), fastcat(1, 2, 3)));
     });
     it('works with auto-reified values', () => {
-      expect(sameFirst(stepcat(expand(3, 'bd'), 'rim'), stepcat(expand(3, 'bd'), pure('rim'))))
+      expect(sameFirst(stepcat(expand(3, 'bd'), 'rim'), stepcat(expand(3, 'bd'), pure('rim'))));
     });
   });
   describe('shrink', () => {

From c01b4c651c54603fd295fc4750e77d9858123b1e Mon Sep 17 00:00:00 2001
From: alex <alex@slab.org>
Date: Thu, 19 Jun 2025 09:06:53 +0100
Subject: [PATCH 4/4] don't trash lists passed to timecat

---
 packages/core/pattern.mjs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/core/pattern.mjs b/packages/core/pattern.mjs
index 59833aea7..6441b7568 100644
--- a/packages/core/pattern.mjs
+++ b/packages/core/pattern.mjs
@@ -2719,8 +2719,7 @@ export function stepcat(...timepats) {
   if (timepats.length === 0) {
     return nothing;
   }
-  const findsteps = (x) => (Array.isArray(x) ? x : [x._steps, x]);
-  timepats = timepats.map(reify);
+  const findsteps = (x) => (Array.isArray(x) ? x : [x._steps ?? 1, x]);
   timepats = timepats.map(findsteps);
   if (timepats.find((x) => x[0] === undefined)) {
     const times = timepats.map((a) => a[0]).filter((x) => x !== undefined);